CONCORD, N.H. — The New Hampshire Senate rejected a bid to repeal the death penalty when its members deadlocked, 12 to 12, Thursday on whether to join the rest of New England in abolishing capital punishment.

In a 195-year-old chamber where rapt senators listened to impassioned appeals from their colleagues, 11 Republicans and one Democrat provided the votes needed to table the bill. The split, after weeks of intense lobbying on both sides of the issue, seemed to buttress the state’s reputation as a conservative iconoclast among more liberal neighbors.

Senator Jeb Bradley of Wolfeboro, the Republican majority leader, said it is unlikely the measure would gain the additional vote needed to bring it off the table for another roll call this session.

“This is what I expected,” Bradley said. “It was obviously a very solemn debate.”

The majority leader, who opposed repeal, said he did not impose party discipline on the issue, which he termed a matter of conscience. Two Republicans joined 10 Democrats in the repeal effort.

The House of Representatives voted overwhelmingly in March to abolish capital punishment in a state where no one has been executed in 75 years and only one person is on death row, a Boston man who fatally shot a Manchester police officer in 2006.

Governor Maggie Hassan, a first-term Democrat, had said she would sign a bill to join 18 other states that have abolished the death penalty. Connecticut, in 2012, was the fifth New England state to vote for repeal.

Police Chief Michael Sielicki of Kensington, president of the state association of police chiefs, called the vote a victory for law enforcement.

“It’s a very personal issue for all of us,” Sielicki said. “I’m glad it remains in effect.”

A Democratic sponsor of the House bill, Renny Cushing of Hampton, said he was disappointed in the vote but believes abolition is inevitable.

“You can see there is real momentum,” said Cushing, whose father was shot and killed at the door of his home in 1988. “Our job is to change one mind at a time.”

Jim Cole/Associated Press

New Hampshire state Sen. Bob Odell spoke in favor of repealing the state’s death penalty.

Cushing said he would work to bring the measure up again in this legislative session. The last day for the Senate to act on House bills is May 15. After that date, a two-thirds majority would be required to suspend the Senate rules before the session ends June 5.

Despite the even split in the Senate, support for the death penalty runs deep in New Hampshire. In a January poll, capital punishment was supported by 58 percent of respondents and opposed by 28 percent, according to the University of New Hampshire Survey Center.

The poll found that even when life in prison was offered as an alternative, the death penalty was favored, 48 percent to 40 percent.

Andrew Smith, director of the survey center, said repeal might need Democratic control of the House, Senate, and governor’s office. The missing piece for the Democrats is the Senate, where Republicans hold 13 of 24 seats.

“I suspect that Republicans in the Senate don’t want to aggravate their GOP base unnecessarily going into the elections this fall, as Republicans are consistently more likely to favor the death penalty than Democrats,” Smith said.

Senator Bette Lasky, a Nashua Democrat, began the debate by urging her colleagues to end what she called a “barbaric practice.”

“It is time for New Hampshire to join our five other New England states and every other civilized democracy in the world,” Lasky said.

“Will our legacy in this chamber today be one of enlightenment and not one of darkness and death?” the senator asked.

Senator Lou D’Allesandro of Manchester, the only Democrat to oppose repeal, countered that the fate of police Officer Michael Briggs, who was killed in 2006 while chasing Michael Addison of Dorchester, Mass., compels lawmakers to retain the death penalty.

Richard Dieter, executive director of the Death Penalty Information Center in Washington, D.C., said the lingering effect of the Briggs killing probably was the most influential factor in the vote.

“You take away that case, and I think the vote would have been different,” said Dieter, whose group acts as a clearinghouse for data on the death penalty. “It’s a small state, and people remember each vote.”

One of the pivotal votes belonged to Senator Russell Prescott, a Republican from Kingston, who had been wavering. “This is the one that gives me peace,” Prescott said afterward about his decision. “I wanted to affirm that our justice system can do its job” and let jurors decide whether a criminal should be executed.

“There are so many good points on all sides,” Prescott said. “I believe that I have heard all arguments.”

Senator David Pierce, a Democrat from Lebanon, said his journey against capital punishment began as a law clerk two decades ago for the Pennsylvania Supreme Court, when he was asked to write an opinion that provided legal justification for an execution.

“I have regretted that opinion ever since,” Pierce said on the floor. “If we want to honor the victim’s life, we need to do that by ending the cycle of violence, not continuing it.”

The death penalty is applicable for a small number of crimes in New Hampshire, including the murder of law enforcement officials while on duty and killings committed during home invasions.

Before the final vote, Lasky offered an unsuccessful amendment to repeal the death penalty only for murders occurring after July 1. However, Bradley argued that such an amendment — which conceivably would have allowed Addison to be put to death even if the state abolished future executions — probably would be unconstitutional.

The US chapter of Amnesty International urged lawmakers who had supported repeal to keep working on the issue.

“If New Hampshire does not end capital punishment, it will only contribute to helping the United States continue to hold its position as one of the top five executioners in the world,” said Steven W. Hawkins, the chapter’s executive director.

Before the Senate convened, dozens of capital punishment opponents formed a quiet ring around the entrance to the state Capitol. The protesters held signs, one of which read “Not In My Name,” as legislators and spectators arrived at the 19th-century granite building.